my @tests = (
    [[2,7,11,15], 9, [0,1]],
    [[2,7,11,15], 9, [1,0]],
    [[3,2,4], 6, [1,2]],
    [[3,2,4], 6, [2,1]],
    [[3,3], 6, [0,1]],
    [[3,3], 6, [1,0]],
);

##</code><code>##

for my $test (@tests) {
    is_deeply
        sort_arrayref(two_sum($test->[INPUT], $test->[TARGET])),
        sort_arrayref($test->[EXPECTED]);
}

##</code><code>##

sub sort_arrayref {
    my ($aref) = @_;

    return [ sort { $a <=> $b } @$aref ];
}

##</code><code>##

1..6
ok 1
ok 2
ok 3
ok 4
ok 5
ok 6